This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We have initiated a study of lipid interactions of a synthetic peptide corresponding to the internal fusion peptide from SARS-CoV (IFP18). Fusion peptide can be classified as an N-terminal or internal, depending on their location relative to the cleavage site of the viral fusion protein. The coronavirus spike protein (S) protein is known to be cleaved at the S1/S2 boundary. This cleavage site is not closely linked to a fusion peptide. It was reported that a synthetic peptide, consisting of 18 resides, immediately C-terminal to a second S2 cleavage site of SARS-CoV (IFP18), promotes lipid mixing. Mutagenesis studies showed that some conserved residues in this sequence of SARS-CoV are critical in viral fusion mediated by SARS-Cov. Thus, this peptide was suggested to be an internal fusion peptide [1]. [1] Madu, I.G., S.L. Roth, S. Belouzard, and G.R. Whittaker. 2009. Characterization of highly conserved domains within the severe acute respiratory syndrome coronavirus spike protein S2 domain with characteristics of a viral fusion peptide. J. Virol. 83:7411-7421.